问题 推断题

(4分)下图是初中化学常见物质转化关系图(个别产物可能略去)。其中A、B常温下均为液态,且组成元素相同;F是大理石的主要成分。Y为氧化物,Z是红色固体,

E为黑色固体。请回答下列问题:

(1)在反应①中,物质X起       作用。

(2)B是     (填化学式)。

(3)反应④的化学方程式为                           。

(4)反应⑤的化学方程式为                             。

答案

F是大理石的主要成分,所以F是碳酸钙,从G和H反应会生成蓝色沉淀,所以H中含有铜离子,E和硫酸反应会生成H,所以H是硫酸铜,E就是氧化铜,C和紫红色固体Z会生成氧化铜,所以C是氧气,Z就是铜,B和氧化物Y反应生成的D和碳酸钠会生成碳酸钙沉淀,所以D就是氢氧化钙,Y就是氧化钙,B就是水,A、B常温下均为液态,且组成元素相同,所以A就是过氧化氢,X就是二氧化锰,经过验证各种物质都满足题意,

(1)二氧化锰在过氧化氢的分解中起加快过氧化氢分解的作用,故答案为:催化;

(2)通过(1)的推导可知A是过氧化氢,F是碳酸钙,故答案为:H2O2,CaCO3

(3)氢氧化钙和碳酸钠反应生成碳酸钙沉淀和氢氧化钠,故答案为:

Ca(OH)2+Na2CO3=2NaOH+CaCO3↓;

(4)氧化铜和硫酸反应生成硫酸铜和水,故答案为:CuO+H2SO4=CuSO4+H2O.

多项选择题 案例分析题
阅读理解

No country in the world has more daily newspapers than the USA. There are almost 2,000 of them, as compared with 180 in Japan, 164 in Argentina and 111 in Britain. The quality of some American papers is extremely high and their views are quoted all over the world. Famous dailies like the Washington Post or the New York Times have a powerful influence all over the country. However, they are not national newspapers in the sense that The Times is in Britain or Le Monde is in France, since each American city has its own daily newspaper. The best of these present detailed description of national and international news, but many tend to limit themselves to state or city news.

 Like the press in most other countries, American newspapers range from the “sensational” which feature crime and gossip(闲谈), to the “serious”, which focus on factual news and the analysis of world events. But with few exceptions, American newspapers try to entertain as well as give information, for they have to compete with the attraction of television.

Just as American newspapers satisfy all tastes, so do they also try to attract readers of all political parties. A few newspapers support extremist(极端主义的) groups on the far right and on the far left, but most daily newspapers try to attract middle-of-the-road Americans who are moderate(中立的). Many of these papers print columns by well-known journalists of different political and social views, in order to present a balanced picture.

As in other countries, American newspapers can be either responsible or irresponsible, but it is generally accepted that the American press serves its country well and that it has more than once courageously exposed political scandals(丑闻) or crimes, for instance, the Watergate Affair(水门事件). The Newspapers drew the attention of the public to the horrors of the Vietnam War.

小题1:There are fewer national newspapers in          .

  A. Britain than in the USA.    B. France than in Britain

  C. the USA than in Britain or France

  D. France than in the USA or Britain

小题2:Most American newspapers try hard to entertain their readers because

.  

A.they have to keep up a good relation with them

B.they have to compete with television

C.they have to write about crime and gossip

D.they have to give factual news in an interesting way小题3:Many American newspapers attract readers of different political preference by          .

A.supporting extremist groups from time to time

B.inviting middle-of-the-road Americans to write articles for them

C.avoiding carrying articles about extremists

D.printing articles representing different political viewpoints小题4:The passage is mainly about             .

A.the characteristics of American newspapers

B.the development of American newspapers

C.the functions of American newspapers

D.the advantages and disadvantages of American newspapers